U.S. patent number 8,171,292 [Application Number 12/420,387] was granted by the patent office on 2012-05-01 for systems, devices, and methods for securely transmitting a security parameter to a computing device.
This patent grant is currently assigned to Research In Motion Limited. Invention is credited to Michael S. Brown, Herbert A. Little.
United States Patent |
8,171,292 |
Brown , et al. |
May 1, 2012 |
Systems, devices, and methods for securely transmitting a security
parameter to a computing device
Abstract
Embodiments of the systems, devices, and methods described
herein generally facilitate the secure transmittal of security
parameters. In accordance with at least one embodiment, a
representation of first data comprising a password is generated at
the first computing device as an image or audio signal. The image
or audio signal is transmitted from the first computing device to
the second computing device. The password is determined from the
image or audio signal at the second computing device. A key
exchange is performed between the first computing device and the
second computing device wherein a key is derived at each of the
first and second computing devices. In at least one embodiment, one
or more security parameters (e.g. one or more public keys) are
exchanged between the first and second computing devices, and
techniques for securing the exchange of security parameters or
authenticating exchanged security parameters are generally
disclosed herein.
Inventors: |
Brown; Michael S. (Waterloo,
CA), Little; Herbert A. (Waterloo, CA) |
Assignee: |
Research In Motion Limited
(Waterloo, Ontario, CA)
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Family
ID: |
42935281 |
Appl.
No.: |
12/420,387 |
Filed: |
April 8, 2009 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20100262828 A1 |
Oct 14, 2010 |
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Current U.S.
Class: |
713/171; 380/259;
380/223; 380/278; 380/279; 380/228 |
Current CPC
Class: |
H04L
63/061 (20130101); H04L 9/3226 (20130101); H04L
9/08 (20130101); H04L 63/20 (20130101); H04L
9/0844 (20130101); H04L 63/18 (20130101); H04L
2209/80 (20130101) |
Current International
Class: |
H04L
9/32 (20060101); H04N 7/167 (20110101); H04L
9/00 (20060101); H04L 9/08 (20060101) |
Field of
Search: |
;713/171
;380/223,228,259,278,279 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1469372 |
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Oct 2004 |
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EP |
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1650894 |
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Apr 2006 |
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EP |
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1659894 |
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May 2006 |
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EP |
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2239918 |
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Oct 2008 |
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EP |
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2239919 |
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Oct 2010 |
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EP |
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Other References
Co-pending U.S. Appl. No. 12/420,421. "Systems, Devices, and
Methods for Securely Transmitting a Security Parameter to a
Computing Device", filed Apr. 8, 2009. cited by other .
Office Action. Co-pending U.S. Appl. No. 12/420,421. Dated: Aug.
31, 2011. cited by other .
Response. Co-pending U.S. Appl. No. 12/420,421. Dated: Nov. 30,
2011. cited by other .
Decision to grant a European Patent pursuant to article 97(1) EPC.
Application No. 09157671.0. Dated: May 12, 2011. cited by other
.
Decision to grant a European Patent pursuant to article 97(1) EPC.
Application No. 09157670.2. Dated: Jul. 14, 2011. cited by other
.
Extended European Search Report. Application No. 09157671.0. Dated:
Aug. 14, 2009. cited by other .
Communication Pursuant to article 94(3) EPC. Application No.
09157671.0. Dated: Nov. 4, 2009. cited by other .
Summons to Attend Oral Proceedings Pursuant to Rule 115(1) EPC.
Application No. 09157671.0. Dated: Apr. 23, 2010. cited by other
.
Provision of the Minutes in accordance with Rule 124(4) EPC.
Application No. 09157671.0. Dated: Oct. 26, 2010. cited by other
.
Communication Under Rule 71(3) EPC. Application No. 09157671.0.
Dated: Nov. 19, 2010. cited by other .
"Using a Two Dimensional Colorized Barcode Solution for
Authentication in Pervasive Computing" by William Claycomb and
Dongwan Shin (2006 ACS/IEEE International Conference on Pervasive
Services; Jun. 26-29, 2006; pp. 173-180). cited by other .
"Talking to strangers: Authentication in ad-hoc wireless networks"
by D. Balfanz, D. K. Smetters, P. Stewart, and H. C. Wong
(Proceedings of Network and Distributed System Security Symposium
2002 (NDSS02); San Diego, CA; Feb. 2002). cited by other .
"Securing Spontaneous Communications in Wireless Pervasive
Computing Environments" by Dongwan Shin (Seventh IEEE International
Symposium on Multimedia; Dec. 12-14, 2005; 6 pp.). cited by other
.
Extended European Search Report. Application No. 09157670.2. Dated:
Aug. 14, 2009. cited by other .
Communication Pursuant to article 94(3) EPC. Application No.
09157670.2. Dated: Nov. 4, 2009. cited by other .
Summons to Attend Oral Proceedings Pursuant to Rule 115(1) EPC.
Application No. 09157670.2. Dated: Apr. 23, 2010. cited by other
.
Provision of the Minutes in accordance with Rule 124(4) EPC.
Application No. 09157670.2. Dated: Nov. 10, 2010. cited by other
.
Communication Under Rule 71(3) EPC. Application No. 09157670.2.
Dated: Jan. 24, 2011. cited by other .
"Visual device identification for security services in ad-hoc
wireless networks" by D. Shin and S. Im (Proceedings of 20th
International Symposium on Computer and Information Sciences
(ISCIS'05); Istanbul, Turkey; Oct. 2005). cited by other.
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Primary Examiner: Reza; Mohammad
Attorney, Agent or Firm: Bereskin & Parr
LLP/S.E.N.C.R.L., s.r.l.
Claims
The invention claimed is:
1. A method of transmitting one or more security parameters from a
first computing device to a second computing device, the method
being performed at the first computing device, the method
comprising: generating an image for transmission to the second
computing device, wherein the image is a representation of first
data, the first data comprising a password, wherein the password is
not derived from the one or more security parameters; transmitting
the image to the second computing device at which the password is
determinable from the image; and performing a key exchange with the
second computing device over a communication channel between the
first and second computing devices, wherein second data is
exchanged between the first and second computing devices in
accordance with a key exchange protocol, such that a key is derived
at each of the first and second computing devices using the
password, and wherein the one or more security parameters is
transmitted to the second computing device during the key exchange;
wherein said performing further comprises computing a confirmation
value based on at least the one or more security parameters and the
key derived at the first computing device, and transmitting the
confirmation value to the second computing device, wherein the one
or more security parameters are authenticated when the confirmation
value is successfully verified at the second computing device; and
wherein the one or more security parameters comprise one or more
public keys stored on the first computing device.
2. The method of claim 1, wherein said transmitting the image to
the second computing device is performed when the first and second
computing devices are in close physical proximity.
3. The method of claim 1, wherein the confirmation value comprises
a keyed-hash message authentication code.
4. The method of claim 1, wherein the key exchange protocol
comprises a SPEKE protocol.
5. The method of claim 1, wherein the image comprises a
barcode.
6. The method of claim 1, wherein at the transmitting, the image is
transmitted via a display of the first computing device.
7. The method of claim 1, wherein the first data further comprises
routing data associated with the first computing device.
8. The method of claim 7, wherein the routing data associated with
the first computing device comprises a PIN associated with the
first computing device, and wherein the communication channel
between the first and second computing devices comprises a
PIN-to-PIN channel.
9. The method of claim 1, further comprising generating the
password, wherein the password is generated as a random number or
string.
10. The method of claim 9, wherein the password is generated for a
single instance of said generating the image.
11. The method of claim 1, further comprising receiving one or more
second security parameters from the second computing device,
receiving a second confirmation value from the second computing
device, and verifying the second confirmation value.
12. The method of claim 1, wherein at least one computing device
selected from the following group comprises a mobile device: the
first computing device, and the second computing device.
13. A first computing device comprising a processor and a memory,
the processor configured to perform a method of transmitting one or
more security parameters to a second computing device by executing
one or more application modules, said one or more application
modules comprising: a module configured to generate an image for
transmission to the second computing device, wherein the image is a
representation of first data, the first data comprising a password,
wherein the password is not derived from the one or more security
parameters; a module configured to transmit the image to the second
computing device at which the password is determinable from the
image; and a module configured to perform a key exchange with the
second computing device over a communication channel between the
first and second computing devices, wherein second data is
exchanged between the first and second computing devices in
accordance with a key exchange protocol, such that a key is derived
at each of the first and second computing devices using the
password, and wherein the one or more security parameters is
transmitted to the second computing device during the key exchange;
wherein said module configured to perform a key exchange is further
configured to compute a confirmation value based on at least the
one or more security parameters and the key derived at the first
computing device, and to transmit the confirmation value to the
second computing device, wherein the one or more security
parameters are authenticated when the confirmation value is
successfully verified at the second computing device and wherein
the one or more security parameters comprise one or more public
keys stored on the first computing device.
14. The first computing device of claim 13, wherein at least one
computing device selected from the following group comprises a
mobile device: the first computing device, and the second computing
device.
15. A non-transitory computer readable storage medium comprising
instructions that, when executed by a processor of a first
computing device, cause the first computing device to perform acts
of a method of transmitting one or more security parameters to a
second computing device, the method performed at the first
computing device, the acts comprising: generating an image for
transmission to the second computing device, wherein the image is a
representation of first data, the first data comprising a password,
wherein the password is not derived from the one or more security
parameters; transmitting the image to the second computing device
at which the password is determinable from the image; and
performing a key exchange with the second computing device over a
communication channel between the first and second computing
devices, wherein second data is exchanged between the first and
second computing devices in accordance with a key exchange
protocol, such that a key is derived at each of the first and
second computing devices using the password, and wherein the one or
more security parameters is transmitted to the second computing
device during the key exchange; wherein said performing further
comprises computing a confirmation value based on at least the one
or more security parameters and the key derived at the first
computing device, and transmitting the confirmation value to the
second computing device, wherein the one or more security
parameters are authenticated when the confirmation value is
successfully verified at the second computing device; and wherein
the one or more security parameters comprise one or more public
keys stored on the first computing device.
16. The medium of claim 15, wherein at least one computing device
selected from the following group comprises a mobile device: the
first computing device, and the second computing device.
Description
FIELD
Embodiments described herein relate generally to the transmittal of
security parameters, and more specifically to the secure
transmittal of security parameters between two computing
devices.
BACKGROUND
Situations where users of computing devices wish to communicate
data present a number of challenges.
Some methods for securely transmitting security parameters (e.g.
public keys) between two computing devices may require either
manual verification of the security parameter by users of the
computing devices (e.g. checking and confirming the public key
fingerprint) or a large amount of infrastructure (e.g. a public key
infrastructure to create and maintain authentic certificates
containing public keys).
BRIEF DESCRIPTION OF THE DRAWINGS
For a better understanding of embodiments of the systems and
methods described herein, and to show more clearly how they may be
carried into effect, reference will be made, by way of example, to
the accompanying drawings in which:
FIG. 1 is a block diagram of a mobile device in one example
implementation;
FIG. 2 is a block diagram of a communication subsystem component of
the mobile device of FIG. 1;
FIG. 3A is a block diagram of a node of a wireless network;
FIG. 3B is a block diagram illustrating components of an example of
a wireless router;
FIG. 4 is a block diagram illustrating components of a host system
in one example configuration;
FIG. 5 is a block diagram illustrating the secure transmittal of
security parameters from one computing device to another computing
device in accordance with at least one embodiment;
FIG. 6 is a flowchart illustrating acts of a method of securely
transmitting a security parameter from one computing device to
another computing device in accordance with at least one
embodiment;
FIG. 7 is a flowchart illustrating acts of a method of securely
transmitting a security parameter from one computing device to
another computing device in accordance with at least one other
embodiment;
FIG. 8 is an example screen capture of the display of a computing
device prompting a user with an option to generate either an image
(e.g. a barcode) or an e-mail message in accordance with at least
one embodiment;
FIG. 9 is an example screen capture of the display of a computing
device wherein a user has selected an option to generate an image
(e.g. a barcode) in accordance with an example embodiment;
FIG. 10 is an example screen capture of the display of a computing
device as it displays an image (e.g. a barcode) for transmission to
another computing device in accordance with an example
embodiment;
FIG. 11 is an example screen capture of the display of a computing
device prompting a user with an option to receive the transmission
of an image (e.g. a barcode) from another computing device in
accordance with an example embodiment;
FIG. 12 is an example screen capture of the display of a computing
device as it instructs a user on how to receive an image (e.g. a
barcode) from another computing device in accordance with an
example embodiment;
FIG. 13 is an example screen capture of the display of a computing
device upon receiving an image (e.g. a barcode) transmitted from
another computing device and upon determining first data from the
image (e.g. a barcode) in accordance with an example embodiment;
and
FIG. 14 is an example screen capture of the display of a computing
device wherein a user has selected an option to generate an e-mail
message in accordance with an example embodiment.
DETAILED DESCRIPTION
Some embodiments of the systems and methods described herein make
reference to a mobile device. A mobile device may be a two-way
communication device with advanced data communication capabilities
having the capability to communicate with other computer systems. A
mobile device may also include the capability for voice
communications. Depending on the functionality provided by a mobile
device, it may be referred to as a data messaging device, a two-way
pager, a cellular telephone with data messaging capabilities, a
wireless Internet appliance, or a data communication device (with
or without telephony capabilities), for example. A mobile device
may communicate with other devices through a network of transceiver
stations.
To aid the reader in understanding the structure of a mobile device
and how it communicates with other devices, reference is made to
FIGS. 1 through 3.
Referring first to FIG. 1, a block diagram of a mobile device in
one example implementation is shown generally as 100. Mobile device
100 comprises a number of components, the controlling component
being microprocessor 102. Microprocessor 102 controls the overall
operation of mobile device 100. Communication functions, including
data and voice communications, may be performed through
communication subsystem 104. Communication subsystem 104 may be
configured to receive messages from and send messages to a wireless
network 200. In one example implementation of mobile device 100,
communication subsystem 104 may be configured in accordance with
the Global System for Mobile Communication (GSM) and General Packet
Radio Services (GPRS) standards. The GSM/GPRS wireless network is
used worldwide and it is expected that these standards may be
supplemented or superseded eventually by Enhanced Data GSM
Environment (EDGE) and Universal Mobile Telecommunications Service
(UMTS), and Ultra Mobile Broadband (UMB), etc. New standards are
still being defined, but it is believed that they will have
similarities to the network behaviour described herein, and it will
also be understood by persons skilled in the art that the
embodiments of the present disclosure are intended to use any other
suitable standards that are developed in the future. The wireless
link connecting communication subsystem 104 with network 200
represents one or more different Radio Frequency (RF) channels,
operating according to defined protocols specified for GSM/GPRS
communications. With newer network protocols, these channels are
capable of supporting both circuit switched voice communications
and packet switched data communications.
Although the wireless network associated with mobile device 100 is
a GSM/GPRS wireless network in one example implementation of mobile
device 100, other wireless networks may also be associated with
mobile device 100 in variant implementations. Different types of
wireless networks that may be employed include, for example,
data-centric wireless networks, voice-centric wireless networks,
and dual-mode networks that can support both voice and data
communications over the same physical base stations. Combined
dual-mode networks include, but are not limited to, Code Division
Multiple Access (CDMA) or CDMA2000 networks, GSM/GPRS networks (as
mentioned above), and future third-generation (3G) networks like
EDGE and UMTS. Some older examples of data-centric networks include
the Mobitex.TM. Radio Network and the DataTAC.TM. Radio Network.
Examples of older voice-centric data networks include Personal
Communication Systems (PCS) networks like GSM and Time Division
Multiple Access (TDMA) systems. Other network communication
technologies that may be employed include, for example, Integrated
Digital Enhanced Network (iDEN.TM.), Evolution-Data Optimized
(EV-DO), and High Speed Packet Access (HSPA), etc.
Microprocessor 102 may also interact with additional subsystems
such as a Random Access Memory (RAM) 106, flash memory 108, display
110, auxiliary input/output (I/O) subsystem 112, serial port 114,
keyboard 116, speaker 118, microphone 120, camera unit 148,
short-range communications subsystem 122 and other device
subsystems 124.
Some of the subsystems of mobile device 100 perform
communication-related functions, whereas other subsystems may
provide "resident" or on-device functions. By way of example,
display 110 and keyboard 116 may be used for both
communication-related functions, such as entering a text message
for transmission over network 200, as well as device-resident
functions such as a calculator or task list. Operating system
software used by microprocessor 102 is typically stored in a
persistent store such as flash memory 108, which may alternatively
be a read-only memory (ROM) or similar storage element (not shown).
Those skilled in the art will appreciate that the operating system,
specific device applications, or parts thereof, may be temporarily
loaded into a volatile store such as RAM 106.
Mobile device 100 may send and receive communication signals over
network 200 after network registration or activation procedures
have been completed. Network access may be associated with a
subscriber or user of a mobile device 100. To identify a
subscriber, mobile device 100 may provide for a Subscriber Identity
Module ("SIM") card 126 (or e.g. a USIM for UMTS, or a CSIM or RUIM
for CDMA) to be inserted in a SIM interface 128 in order to
communicate with a network. SIM 126 may be one example type of a
conventional "smart card" used to identify a subscriber of mobile
device 100 and to personalize the mobile device 100, among other
things. Without SIM 126, mobile device 100 may not be fully
operational for communication with network 200. By inserting SIM
126 into SIM interface 128, a subscriber may access all subscribed
services. Services may include, without limitation: web browsing
and messaging such as e-mail, voice mail, Short Message Service
(SMS), and Multimedia Messaging Services (MMS). More advanced
services may include, without limitation: point of sale, field
service and sales force automation. SIM 126 may include a processor
and memory for storing information. Once SIM 126 is inserted in SIM
interface 128, it may be coupled to microprocessor 102. In order to
identify the subscriber, SIM 126 may contain some user parameters
such as an International Mobile Subscriber Identity (IMSI). By
using SIM 126, a subscriber may not necessarily be bound by any
single physical mobile device. SIM 126 may store additional
subscriber information for a mobile device as well, including
datebook (or calendar) information and recent call information.
Mobile device 100 may be a battery-powered device and may comprise
a battery interface 132 for receiving one or more rechargeable
batteries 130. Battery interface 132 may be coupled to a regulator
(not shown), which assists battery 130 in providing power V+ to
mobile device 100. Although current technology makes use of a
battery, future technologies such as micro fuel cells may provide
power to mobile device 100. In some embodiments, mobile device 100
may be solar-powered.
Microprocessor 102, in addition to its operating system functions,
enables execution of software applications on mobile device 100. A
set of applications that control basic device operations, including
data and voice communication applications, may be installed on
mobile device 100 during its manufacture. Another application that
may be loaded onto mobile device 100 is a personal information
manager (PIM). A PIM has functionality to organize and manage data
items of interest to a subscriber, such as, but not limited to,
e-mail, calendar events, voice mails, appointments, and task items.
A PIM application has the ability to send and receive data items
via wireless network 200. PIM data items may be seamlessly
integrated, synchronized, and updated via wireless network 200 with
the mobile device subscriber's corresponding data items stored
and/or associated with a host computer system. This functionality
may create a mirrored host computer on mobile device 100 with
respect to such items. This can be particularly advantageous where
the host computer system is the mobile device subscriber's office
computer system.
Additional applications may also be loaded onto mobile device 100
through network 200, auxiliary I/O subsystem 112, serial port 114,
short-range communications subsystem 122, or any other suitable
subsystem 124. This flexibility in application installation
increases the functionality of mobile device 100 and may provide
enhanced on-device functions, communication-related functions, or
both. For example, secure communication applications may enable
electronic commerce functions and other such financial transactions
to be performed using mobile device 100.
Serial port 114 enables a subscriber to set preferences through an
external device or software application and extends the
capabilities of mobile device 100 by providing for information or
software downloads to mobile device 100 other than through a
wireless communication network. The alternate download path may,
for example, be used to load an encryption key onto mobile device
100 through a direct and thus reliable and trusted connection to
provide secure device communication.
Short-range communications subsystem 122 provides for communication
between mobile device 100 and different systems or devices, without
the use of network 200. For example, subsystem 122 may include an
infrared device and associated circuits and components for
short-range communication. Examples of short-range communication
include standards developed by the Infrared Data Association
(IrDA), Bluetooth.RTM., and the 802.11 family of standards
(Wi-Fi.RTM.) developed by IEEE.
In use, a received signal such as a text message, an e-mail
message, or web page download is processed by communication
subsystem 104 and input to microprocessor 102. Microprocessor 102
then processes the received signal for output to display 110 or
alternatively to auxiliary I/O subsystem 112. A subscriber may also
compose data items, such as e-mail messages, for example, using
keyboard 116 in conjunction with display 110 and possibly auxiliary
I/O subsystem 112. Auxiliary subsystem 112 may include devices such
as: a touch screen, mouse, track ball, infrared fingerprint
detector, or a roller wheel with dynamic button pressing
capability. Keyboard 116 may comprise an alphanumeric keyboard
and/or telephone-type keypad, for example. A composed item may be
transmitted over network 200 through communication subsystem
104.
For voice communications, the overall operation of mobile device
100 may be substantially similar, except that the received signals
may be processed and output to speaker 118, and signals for
transmission may be generated by microphone 120. Alternative voice
or audio I/O subsystems, such as a voice message recording
subsystem, may also be implemented on mobile device 100. Although
voice or audio signal output is accomplished primarily through
speaker 118, display 110 may also be used to provide additional
information such as the identity of a calling party, duration of a
voice call, or other voice call related information.
Referring now to FIG. 2, a block diagram of the communication
subsystem component 104 of FIG. 1 is shown. Communication subsystem
104 may comprise a receiver 150, a transmitter 152, one or more
embedded or internal antenna elements 154, 156, Local Oscillators
(LOs) 158, and a processing module such as a Digital Signal
Processor (DSP) 160.
The particular design of communication subsystem 104 may be
dependent upon the network 200 in which mobile device 100 is
intended to operate; thus, it should be understood that the design
illustrated in FIG. 2 serves only as one example. Signals received
by antenna 154 through network 200 are input to receiver 150, which
may perform such common receiver functions as signal amplification,
frequency down conversion, filtering, channel selection, and
analog-to-digital (ND) conversion. ND conversion of a received
signal allows more complex communication functions such as
demodulation and decoding to be performed in DSP 160. In a similar
manner, signals to be transmitted are processed, including
modulation and encoding, by DSP 160. These DSP-processed signals
are input to transmitter 152 for digital-to-analog (D/A)
conversion, frequency up conversion, filtering, amplification and
transmission over network 200 via antenna 156. DSP 160 not only
processes communication signals, but also provides for receiver and
transmitter control. For example, the gains applied to
communication signals in receiver 150 and transmitter 152 may be
adaptively controlled through automatic gain control algorithms
implemented in DSP 160.
The wireless link between mobile device 100 and a network 200 may
contain one or more different channels, typically different RF
channels, and associated protocols used between mobile device 100
and network 200. A RF channel is generally a limited resource,
typically due to limits in overall bandwidth and limited battery
power of mobile device 100.
When mobile device 100 is fully operational, transmitter 152 may be
typically keyed or turned on only when it is sending to network 200
and may otherwise be turned off to conserve resources. Similarly,
receiver 150 may be periodically turned off to conserve power until
it is needed to receive signals or information (if at all) during
designated time periods.
Referring now to FIG. 3A, a block diagram of a node of a wireless
network is shown as 202. In practice, network 200 comprises one or
more nodes 202. Mobile device 100 communicates with a node 202
within wireless network 200. In the example implementation of FIG.
3A, node 202 is configured in accordance with GPRS and GSM
technologies; however, in other embodiments, different standards
may be implemented as discussed in more detail above. Node 202
includes a base station controller (BSC) 204 with an associated
tower station 206, a Packet Control Unit (PCU) 208 added for GPRS
support in GSM, a Mobile Switching Center (MSC) 210, a Home
Location Register (HLR) 212, a Visitor Location Registry (VLR) 214,
a Serving GPRS Support Node (SGSN) 216, a Gateway GPRS Support Node
(GGSN) 218, and a Dynamic Host Configuration Protocol (DHCP) server
220. This list of components is not meant to be an exhaustive list
of the components of every node 202 within a GSM/GPRS network, but
rather a list of components that are commonly used in
communications through network 200.
In a GSM network, MSC 210 is coupled to BSC 204 and to a landline
network, such as a Public Switched Telephone Network (PSTN) 222 to
satisfy circuit switched requirements. The connection through PCU
208, SGSN 216 and GGSN 218 to the public or private network
(Internet) 224 (also referred to herein generally as a shared
network infrastructure) represents the data path for GPRS capable
mobile devices. In a GSM network extended with GPRS capabilities,
BSC 204 also contains a Packet Control Unit (PCU) 208 that connects
to SGSN 216 to control segmentation, radio channel allocation and
to satisfy packet switched requirements. To track mobile device
location and availability for both circuit switched and packet
switched management, HLR 212 is shared between MSC 210 and SGSN
216. Access to VLR 214 is controlled by MSC 210.
Station 206 may be a fixed transceiver station. Station 206 and BSC
204 together may form the fixed transceiver equipment. The fixed
transceiver equipment provides wireless network coverage for a
particular coverage area commonly referred to as a "cell". The
fixed transceiver equipment transmits communication signals to and
receives communication signals from mobile devices within its cell
via station 206. The fixed transceiver equipment normally performs
such functions as modulation and possibly encoding and/or
encryption of signals to be transmitted to the mobile device in
accordance with particular, usually predetermined, communication
protocols and parameters, under control of its controller. The
fixed transceiver equipment similarly demodulates and possibly
decodes and decrypts, if necessary, any communication signals
received from mobile device 100 within its cell. Communication
protocols and parameters may vary between different nodes. For
example, one node may employ a different modulation scheme and
operate at different frequencies than other nodes.
For all mobile devices 100 registered with a specific network,
permanent configuration data such as a user profile may be stored
in HLR 212. HLR 212 may also contain location information for each
registered mobile device and can be queried to determine the
current location of a mobile device. MSC 210 is responsible for a
group of location areas and stores the data of the mobile devices
currently in its area of responsibility in VLR 214. Further VLR 214
also contains information on mobile devices that are visiting other
networks. The information in VLR 214 includes part of the permanent
mobile device data transmitted from HLR 212 to VLR 214 for faster
access. By moving additional information from a remote HLR 212 node
to VLR 214, the amount of traffic between these nodes can be
reduced so that voice and data services can be provided with faster
response times while requiring less use of computing resources.
SGSN 216 and GGSN 218 are elements that may be added for GPRS
support; namely packet switched data support, within GSM. SGSN 216
and MSC 210 have similar responsibilities within wireless network
200 by keeping track of the location of each mobile device 100.
SGSN 216 also performs security functions and access control for
data traffic on network 200. GGSN 218 provides internetworking
connections with external packet switched networks and connects to
one or more SGSNs 216 via an Internet Protocol (IP) backbone
network operated within the network 200. During normal operations,
a given mobile device 100 performs a "GPRS Attach" to acquire an IP
address and to access data services. This normally is not present
in circuit switched voice channels as Integrated Services Digital
Network (ISDN) addresses may be generally used for routing incoming
and outgoing calls. Currently, GPRS capable networks may use
private, dynamically assigned IP addresses, thus requiring a DHCP
server 220 connected to the GGSN 218. There are many mechanisms for
dynamic IP assignment, including using a combination of a Remote
Authentication Dial-In User Service (RADIUS) server and DHCP
server, for example. Once the GPRS Attach is complete, a logical
connection is established from a mobile device 100, through PCU
208, and SGSN 216 to an Access Point Node (APN) within GGSN 218,
for example. The APN represents a logical end of an IP tunnel that
can either access direct Internet compatible services or private
network connections. The APN also represents a security mechanism
for network 200, insofar as each mobile device 100 must be assigned
to one or more APNs and mobile devices 100 cannot generally
exchange data without first performing a GPRS Attach to an APN that
it has been authorized to use. The APN may be considered to be
similar to an Internet domain name such as
"myconnection.wireless.com".
Once the GPRS Attach is complete, a tunnel is created and all
traffic is exchanged within standard IP packets using any protocol
that can be supported in IP packets. This includes tunneling
methods such as IP over IP as in the case with some IPSecurity
(IPsec) connections used with Virtual Private Networks (VPN). These
tunnels are also referred to as Packet Data Protocol (PDP) Contexts
and there are a limited number of these available in the network
200. To maximize use of the PDP Contexts, network 200 will run an
idle timer for each PDP Context to determine if there is a lack of
activity. When a mobile device 100 is not using its PDP Context,
the PDP Context can be deallocated and the IP address returned to
the IP address pool managed by DHCP server 220.
Mobile device 100 may communicate with a host system 250 through a
node 202 of wireless network 200 and a shared network
infrastructure 224 such as a service provider network or the public
Internet. Access to the host system may also be provided through
one or more routers (e.g. situated between the shared network
infrastructure 224 and node 202), such as a wireless router
illustrated in FIG. 3B.
Referring to FIG. 3B, a number of components of an example of a
wireless router 26 are illustrated. It will be understood that
wireless router 26 may comprise different and/or additional
components not shown in FIG. 3B.
One component that may be present but not directly part of the
wireless router 26 is an Internet firewall 27, which may be
off-the-shelf and would protect the wireless router 26 at a lower
IP-layer type protocol. Once through the firewall, the host system
250 may connect to one of a plurality of host interface handlers
(HIHs) 30. There can be any number of HIHs depending on the number
of hosts that are configured and required in the system. The HIH 30
may use various parts of the database 31 to confirm and register
the incoming host connection. The known hosts 31a sub-component of
the database may provide a way of validating that the host is known
and marking its state as `present` once the host is connected and
authorized. Once the host connection is established, a secure and
authenticated point-to-point communication connection may be ready
for the exchange of data between the host system 250 or service and
the wireless router 26. There may be a plurality of such
communication connections between the wireless router 26 and a
plurality of host systems 250 (e.g. as identified by 250a, 250b,
250c) or services.
Another component, which may work closely with the HIH 30 is called
the wireless transport handler (WTH) 36. The WTH 36 takes
responsibility for data item transfer to and from the mobile device
100. Depending on the load of traffic, and the number of mobile
devices 100 in the system, there may be a plurality of WTH 36
components operating in the system. The network backbone 37, using
something like a TIBCO queuing system, combined with the work
dispatcher 32, may allow each component of the system to scale as
large as needed.
The next component is the network interface adapter (NIA) 38, which
could have a communications link directly to the WTH 36, or the NIA
38 could be accessible via the network backbone 37. The NIA 38 may
provide a direct interface to the wireless network 200 being
supported. Since many of the current wireless data networks 200 may
have unique communication connection requirements, this component
can buffer the other wireless router components from many of the
specific nuances of the particular wireless network it is in
communication with. The NIA 38 may be used to isolate the WTH 36
from much of the details of communication links and physical
interface requirements of each wireless network 200. There could be
any number of wireless networks 200, all with their own connection
methods (e.g. shown as 200a, 200b, 200c). In some cases, a
proprietary protocol over X.25 may be employed, in the Mobitex or
Datatac networks, for example. In other cases, a proprietary
protocol over TCP/IP may be employed, like in newer version of the
Datatac network, for example. In other cases, an IP connection may
be employed, supporting either a TCP or UDP data exchange method,
like the CDMA, W-CDMA, and GPRS networks.
To further enhance the wireless router 26 there may be other
support components that could either exist separate, or be built
into a single component. The first of these may be a work
dispatcher 32. One of the functions of the work dispatcher 32, can
be to assign a specific WTH 36 to a mobile device 100 so that all
data items are routed through the same WTH 36. If a WTH 36 fails,
the work dispatcher 32 can find a new WTH 36 to take its place.
Additionally, if one WTH 36 becomes too busy or is handling an
undesirably large traffic load, the work dispatcher 32 can assign
data items that are to be routed to the mobile devices 100 to
instead round robin to multiple WTHs 36. This is one example of how
the fault tolerant and scalable system is built, and a fault
tolerant queuing system like TIBCO may solve this problem very
easily. In the other direction, the work dispatcher 36 can find the
correct HIH 30 to accept data items from mobile devices 100. Since
a host system 250 may connect to any HIH 30, the work dispatcher 36
finds the HIH 30 that has responsibility for or is associated with
the host-router communication connection initiated by the correct
host system 250, and routes the data appropriately.
Another component in the wireless router 26 that is shown in the
example, is the peer-to-peer (P2P) messaging component 34. This
component may provide peer-to-peer message routing facility, which
can allow mobile devices 100 to send directly to one or more other
mobile devices 100, e.g. multi-cast messages. The P2P component 34
can perform the functions similar to an Instant Messaging gateway,
but in this case for mobile devices 100. In some networks, where
the mobile's identity might not be static, a mobile device 100
cannot easily send a message to another mobile device 100. In other
networks, SMS (short message service) may solve this problem and
provides a limited 160 character data exchange. The wireless router
26 may have a store and forward structure that permits it to offer
SMS and wireless messaging simultaneously to all wireless devices
100.
The wireless router 26, in this example, hosts a peer-to-peer
messaging server 80, which utilizes a PIN-to-PIN protocol 82 and a
message cache 316, all of which may be considered components of the
peer-to-peer messaging component 34. Personal identification
numbers (PINs) may be used to address messages, for example. Such a
PIN-based messaging system may be implemented using a server-based
communication infrastructure, such as one that provides email, SMS,
voice, Internet and other communications. Wireless router 26 may be
particularly suitable for hosting a peer-to-peer messaging server
80. In a PIN-based messaging protocol 82, a message may have
associated therewith a PIN corresponding to the mobile device 100
which has sent the message (source) and one or more destination
PINs identifying each intended recipient (destination(s)). When
conducting a PIN-to-PIN message exchange, mobile devices may
communicate directly with the wireless router 26 in a client based
exchange where, similar to other peer-to-peer programs, an
intermediate server is not required. Upon obtaining one or more
recipient PINs according to the PIN-to-PIN protocol 82, the
wireless router 26 may then route the message to all intended
recipients associated with devices having such PINs. The wireless
router 26 typically also provides a delivery confirmation to the
original sender, which may or may not be displayed to the user, and
the mobile device 100 can use an exchange of messages pertaining to
in and out of coverage situations to update presence information on
the mobile device 100. The destination device can also provide such
delivery information. The wireless router 26 may hold messages
until they are successfully delivered. Alternatively, if delivery
cannot be made after a certain timeout period, the wireless router
26 may provide a response indicating a failed delivery. The
wireless router 26 may choose to expire message if a certain
waiting period lapses. In such cases, the mobile device 100 may
then choose whether or not to resend the message 8.
Registration and billing are two other components 33. These two
components could be separated or merged. Registration may involve
keeping track of all valid mobile devices 100 and tracking their
location when they make major wireless network 200 changes. These
changes are propagated to the associated database 31 and used by
the work dispatcher 32 for important work assignment decisions. For
example, if a mobile device 100 travels to another country it might
be necessary to move the responsibility of data item delivery to
another WTH 36 component. As part of the registration function, the
user of the mobile device 100 may be provided with added security.
Services and mobile devices must be registered and authenticated
before they can exchange data.
The billing component may keep a running tally of the services and
amounts of data exchanged between each host system 250 and each
mobile device 100. The billing component receives messages via the
network backbone 37. For example, by using a TIBCO architecture it
would be possible to broadcast billing messages to a group of
billing components 33. Depending on the load of traffic, multiple
billing components 33 could be processing and saving the billing
information to the database 31. Each record could have lots of
information pertinent to generating complex and relevant billing
information. For example, it might be possible to save the size of
the data exchanged, the time of day, the duration, the type of
service access and other key pricing elements.
Referring now to FIG. 4, a block diagram illustrating components of
a host system in one example configuration is shown. Host system
250 will typically be a corporate office or other local area
network (LAN), but may instead be a home office computer or some
other private system, for example, in variant implementations. In
this example shown in FIG. 4, host system 250 is depicted as a LAN
of an organization to which a user of mobile device 100
belongs.
LAN 250 comprises a number of network components connected to each
other by LAN connections 260. For instance, a user's desktop
computing device ("desktop computer") 262a with an accompanying
cradle 264 for the user's mobile device 100 may be situated on LAN
250. Cradle 264 for mobile device 100 may be coupled to computer
262a by a serial or a Universal Serial Bus (USB) connection, for
example. Other user computers 262b are also situated on LAN 250,
and each may or may not be equipped with an accompanying cradle 264
for a mobile device. Cradle 264 facilitates the loading of
information (e.g. PIM data, private symmetric encryption keys to
facilitate secure communications between mobile device 100 and LAN
250) from user computer 262a to mobile device 100, and may be
particularly useful for bulk information updates often performed in
initializing mobile device 100 for use. The information downloaded
to mobile device 100 may include S/MIME certificates or PGP keys
used in the exchange of messages.
It will be understood by persons skilled in the art that user
computers 262a, 262b will typically be also connected to other
peripheral devices not explicitly shown in FIG. 4. Furthermore,
only a subset of network components of LAN 250 are shown in FIG. 4
for ease of exposition, and it will be understood by persons
skilled in the art that LAN 250 will comprise additional components
not explicitly shown in FIG. 4, for this example configuration.
More generally, LAN 250 may represent a smaller part of a larger
network [not shown] of the organization, and may comprise different
components and/or be arranged in different topologies than that
shown in the example of FIG. 4.
In this example, mobile device 100 communicates with LAN 250
through a node 202 of wireless network 200 and a shared network
infrastructure 224 such as a service provider network or the public
Internet. Access to LAN 250 may be provided through one or more
routers [not shown], and computing devices of LAN 250 may operate
from behind a firewall or proxy server 266.
In a variant implementation, LAN 250 comprises a wireless VPN
router [not shown] to facilitate data exchange between the LAN 250
and mobile device 100. The concept of a wireless VPN router is new
in the wireless industry and implies that a VPN connection can be
established directly through a specific wireless network to mobile
device 100. The possibility of using a wireless VPN router has only
recently been available and could be used when the new Internet
Protocol (IP) Version 6 (IPV6) arrives into IP-based wireless
networks. This new protocol will provide enough IP addresses to
dedicate an IP address to every mobile device, making it possible
to push information to a mobile device at any time. An advantage of
using a wireless VPN router is that it could be an off-the-shelf
VPN component, not requiring a separate wireless gateway and
separate wireless infrastructure to be used. A VPN connection may
include, for example, a Transmission Control Protocol (TCP)/IP or
User Datagram Protocol (UDP)/IP connection to deliver the messages
directly to mobile device 100 in this variant implementation.
Messages intended for a user of mobile device 100 are initially
received by a message server 268 of LAN 250. Such messages may
originate from any of a number of sources. For instance, a message
may have been sent by a sender from a computer 262b within LAN 250,
from a different mobile device [not shown] connected to wireless
network 200 or to a different wireless network, or from a different
computing device or other device capable of sending messages, via
the shared network infrastructure 224, and possibly through an
application service provider (ASP) or Internet service provider
(ISP), for example.
Message server 268 typically acts as the primary interface for the
exchange of messages, particularly e-mail messages, within the
organization and over the shared network infrastructure 224. Each
user in the organization that has been set up to send and receive
messages is typically associated with a user account managed by
message server 268. One example of a message server 268 is a
Microsoft Exchange.TM. Server. In some implementations, LAN 250 may
comprise multiple message servers 268. Message server 268 may also
be configured to provide additional functions beyond message
management, including the management of data associated with
calendars and task lists, for example.
When messages are received by message server 268, they are
typically stored in a message store [not explicitly shown], from
which messages can be subsequently retrieved and delivered to
users. For instance, an e-mail client application operating on a
user's computer 262a may request the e-mail messages associated
with that user's account stored on message server 268. These
messages may then typically be retrieved from message server 268
and stored locally on computer 262a.
When operating mobile device 100, the user may wish to have e-mail
messages retrieved for delivery to the mobile device 100. An e-mail
client application operating on mobile device 100 may request
messages associated with the user's account from message server
268. The e-mail client may be configured (either by the user or by
an administrator, possibly in accordance with an organization's
information technology (IT) policy) to make this request at the
direction of the user, at some pre-defined time interval, or upon
the occurrence of some pre-defined event. In some implementations,
mobile device 100 is assigned its own e-mail address, and messages
addressed specifically to mobile device 100 may be automatically
redirected to mobile device 100 as they are received by message
server 268.
To facilitate the wireless communication of messages and
message-related data between mobile device 100 and components of
LAN 250, a number of wireless communications support components 270
may be provided. In this example implementation, wireless
communications support components 270 may comprise a message
management server 272, for example. Message management server 272
may be used to specifically provide support for the management of
messages, such as e-mail messages, that are to be handled by mobile
devices. Generally, while messages are still stored on message
server 268, message management server 272 may be used to control
when, if, and how messages should be sent to mobile device 100.
Message management server 272 also facilitates the handling of
messages composed on mobile device 100, which are sent to message
server 268 for subsequent delivery.
For example, message management server 272 may: monitor the user's
"mailbox" (e.g. the message store associated with the user's
account on message server 268) for new e-mail messages; apply
user-definable filters to new messages to determine if and how the
messages will be relayed to the user's mobile device 100; compress
and encrypt new messages (e.g. using an encryption technique such
as Data Encryption Standard (DES) or Triple DES) and push them to
mobile device 100 via the shared network infrastructure 224 and
wireless network 200; and receive messages composed on mobile
device 100 (e.g. encrypted using Triple DES), decrypt and
decompress the composed messages, re-format the composed messages
if desired so that they will appear to have originated from the
user's computer 262a, and re-route the composed messages to message
server 268 for delivery.
Certain properties or restrictions associated with messages that
are to be sent from and/or received by mobile device 100 can be
defined (e.g. by an administrator in accordance with IT policy) and
enforced by message management server 272. These may include
whether mobile device 100 may receive encrypted and/or signed
messages, minimum encryption key sizes, whether outgoing messages
must be encrypted and/or signed, and whether copies of all secure
messages sent from mobile device 100 are to be sent to a
pre-defined copy address, for example.
Message management server 272 may also be configured to provide
other control functions, such as only pushing certain message
information or pre-defined portions (e.g. "blocks") of a message
stored on message server 268 to mobile device 100. For example,
when a message is initially retrieved by mobile device 100 from
message server 268, message management server 272 is configured to
push only the first part of a message to mobile device 100, with
the part being of a pre-defined size (e.g. 2 KB). The user can then
request more of the message, to be delivered in similar-sized
blocks by message management server 272 to mobile device 100,
possibly up to a maximum pre-defined message size.
Accordingly, message management server 272 facilitates better
control over the type of data and the amount of data that is
communicated to mobile device 100, and can help to minimize
potential waste of bandwidth or other resources.
It will be understood by persons skilled in the art that message
management server 272 need not be implemented on a separate
physical server in LAN 250 or other network. For example, some or
all of the functions associated with message management server 272
may be integrated with message server 268, or some other server in
LAN 250. Furthermore, LAN 250 may comprise multiple message
management servers 272, particularly in variant implementations
where a large number of mobile devices are supported.
While Simple Mail Transfer Protocol (SMTP), RFC822 headers, and
Multipurpose Internet Mail Extensions (MIME) body parts may be used
to define the format of a typical e-mail message not requiring
encoding, Secure/MIME (S/MIME), a version of the MIME protocol, may
be used in the communication of encoded messages (i.e. in secure
messaging applications). S/MIME enables end-to-end authentication
and confidentiality, and provides data integrity and privacy from
the time an originator of a message sends a message until it is
decoded and read by the message recipient. Other standards and
protocols may be employed to facilitate secure message
communication, such as Pretty Good Privacy.TM. (PGP) and variants
of PGP such as OpenPGP, for example. It will be understood that
where reference is generally made to "PGP" herein, the term is
intended to encompass any of a number of variant implementations
based on the more general PGP scheme.
Secure messaging protocols such as S/MIME and PGP-based protocols
rely on public and private encryption keys to provide
confidentiality and integrity. Data encoded using a private key of
a private key/public key pair can only be decoded using the
corresponding public key of the pair, and data encoded using a
public key of a private key/public key pair can only be decoded
using the corresponding private key of the pair. It is intended
that private key information never be made public, whereas public
key information is shared.
For example, if a sender wishes to send message data to a recipient
in encrypted form, the recipient's public key is used to encrypt
the message data, which can then be decrypted only using the
recipient's private key. Alternatively, in some encoding
techniques, a one-time session key is generated and used to encrypt
the message data, typically with a symmetric encryption technique
(e.g. Triple DES). The session key is then encrypted using the
recipient's public key (e.g. with a public key encryption algorithm
such as RSA), which can then be decrypted only using the
recipient's private key. The decrypted session key can then be used
to decrypt the encrypted message data. The message header may
comprise data specifying the particular encryption scheme that must
be used to decrypt the encrypted message data. Other encryption
techniques based on public key cryptography may be used in variant
implementations. However, in each of these cases, only the
recipient's private key may be used to facilitate successful
decryption of the encrypted message data, and in this way, the
confidentiality of that data can be maintained.
As a further example, a sender may sign message data using a
digital signature. A digital signature generally comprises a digest
of the message data being signed (e.g. a hash of the message data
being signed) encoded using the sender's private key, which can
then be appended to the outgoing message. To verify the digital
signature when received, the recipient uses the same technique as
the sender (e.g. using the same standard hash algorithm) to obtain
a digest of the received message data. The recipient also uses the
sender's public key to decode the digital signature, in order to
obtain what should be a matching digest for the received message
data. If the digests of the received message do not match, this
suggests that either the message data was changed during transport
and/or the message data did not originate from the sender whose
public key was used for verification. Digital signature algorithms
are designed in such a way that only someone with knowledge of the
sender's private key should be able to encode a digital signature
that the recipient will decode correctly using the sender's public
key. Therefore, by verifying a digital signature in this way,
authentication of the sender and message integrity can be
maintained.
When reference is made to the application of encoding to message
data, this means that the message data is encoded using an encoding
technique. As noted above, an act of encoding message data may
include either encrypting the message data or signing the message
data. As used in this disclosure, "signed and/or encrypted" means
signed or encrypted or both.
In S/MIME, the authenticity of public keys used in these operations
may be validated using certificates. A certificate is a digital
document issued, for example, by a certificate authority (CA).
Certificates are used to authenticate the association between users
and their public keys, and essentially, provides a level of trust
in the authenticity of the users' public keys. Certificates contain
information about the certificate holder, with certificate contents
typically formatted in accordance with an accepted standard (e.g.
X.509). The certificates are typically digitally signed by the
certificate authority.
In PGP-based systems, a PGP key is used, which is like an S/MIME
certificate in that it contains public information including a
public key and information on the key holder or owner. Unlike
S/MIME certificates, however, PGP keys are not generally issued by
a certificate authority, and the level of trust in the authenticity
of a PGP key typically requires verifying that a trusted individual
has vouched for the authenticity of a given PGP key.
Standard e-mail security protocols typically facilitate secure
message transmission between non-mobile computing devices (e.g.
computers 262a, 262b of FIG. 4; remote desktop devices). In order
that signed messages received from senders may be read from mobile
device 100 and that encrypted messages be sent from mobile device
100, mobile device 100 may be configured to store public keys (e.g.
in S/MIME certificates, PGP keys) of other individuals. Keys stored
on a user's computer 262a may be downloaded from computer 262a to
mobile device 100 through cradle 264, for example.
Mobile device 100 may also be configured to store the private key
of the public key/private key pair associated with the user, so
that the user of mobile device 100 can sign outgoing messages
composed on mobile device 100, and decrypt messages sent to the
user encrypted with the user's public key. The private key may be
downloaded to mobile device 100 from the user's computer 262a
through cradle 264, for example. The private key may be exchanged
between the computer 262a and mobile device 100 so that the user
may share one identity and one method for accessing messages.
User computers 262a, 262b can obtain S/MIME certificates and PGP
keys from a number of sources, for storage on computers 262a, 262b
and/or mobile devices (e.g. mobile device 100) in a key store, for
example. The sources of these certificates and keys may be private
(e.g. dedicated for use within an organization) or public, may
reside locally or remotely, and may be accessible from within an
organization's private network or through the Internet, for
example. In the example shown in FIG. 4, multiple public key
infrastructure (PKI) servers 280 associated with the organization
reside on LAN 250. PKI servers 280 include a CA server 282 that may
be used for issuing S/MIME certificates, a Lightweight Directory
Access Protocol (LDAP) server 284 that may be used to search for
and download S/MIME certificates and/or PGP keys (e.g. for
individuals within the organization), and an Online Certificate
Status Protocol (OCSP) server 286 that may be used to verify the
revocation status of S/MIME certificates, for example.
Certificates and/or PGP keys may be retrieved from LDAP server 284
by a user computer 262a, for example, to be downloaded to mobile
device 100 via cradle 264. However, in a variant implementation,
LDAP server 284 may be accessed directly (i.e. "over the air" in
this context) by mobile device 100, and mobile device 100 may
search for and retrieve individual certificates and PGP keys
through a mobile data server 288. Similarly, mobile data server 288
may be configured to allow mobile device 100 to directly query OCSP
server 286 to verify the revocation status of S/MIME
certificates.
In variant implementations, only selected PKI servers 280 may be
made accessible to mobile devices (e.g. allowing certificates to be
downloaded only from a user's computer 262a, 262b, while allowing
the revocation status of certificates to be checked from mobile
device 100).
In variant implementations, certain PKI servers 280 may be made
accessible only to mobile devices registered to particular users,
as specified by an IT administrator, possibly in accordance with an
IT policy, for example.
Other sources of S/MIME certificates and PGP keys [not shown] may
include a Windows certificate or key store, another secure
certificate or key store on or outside LAN 250, and smart cards,
for example.
Situations where users of computing devices wish to communicate
data present a number of challenges. A primary concern is the
security of the communication, which may often be wireless.
Specifically of concern is the authenticity and confidentiality of
the data being communicated as an attacker within the transmission
range of the wireless communication channel may easily tamper with
or monitor the data being communicated. Some methods for securely
transmitting security parameters (e.g. public keys) between two
computing devices may require either manual verification of the
security parameter by users of the computing devices (e.g. checking
and confirming the public key fingerprint) or a large amount of
infrastructure (e.g. a public key infrastructure to create and
maintain authentic certificates containing public keys).
Embodiments of the systems, devices, and methods described herein
generally facilitate the secure transmittal of security parameters
from one computing device to another computing device.
In one broad aspect, there is provided a system, device, and method
of transmitting one or more security parameters from a first
computing device to a second computing device, the method performed
at the first computing device, the method comprising: generating an
image or audio signal for transmission to the second computing
device, wherein the image or audio signal is a representation of
first data, the first data comprising a password, wherein the
password is not derived from the one or more security parameters;
transmitting the image or audio signal to the second computing
device at which the password is determinable from the image or
audio signal; performing a key exchange with the second computing
device over a communication channel between the first and second
computing devices, wherein second data is exchanged between the
first and second computing devices in accordance with a key
exchange protocol, such that an encryption key is derived at each
of the first and second computing devices using the password;
encrypting the one or more security parameters with the encryption
key or a session key derived from the encryption key; and
transmitting the encrypted one or more security parameters to the
second computing device. In some embodiments, the method performed
at the first computing device further comprises receiving one or
more encrypted second security parameters from the second computing
device, and decrypting the one or more encrypted second security
parameters using the encryption key or a session key derived from
the encryption key.
In another broad aspect, there is provided a system, device, and
method of transmitting one or more security parameters from a first
computing device to a second computing device, the method performed
at the first computing device, the method comprising: generating an
image or audio signal for transmission to the second computing
device, wherein the image or audio signal is a representation of
first data, the first data comprising a password, wherein the
password is not derived from the one or more security parameters;
transmitting the image or audio signal to the second computing
device at which the password is determinable from the image or
audio signal; and performing a key exchange with the second
computing device over a communication channel between the first and
second computing devices, wherein second data is exchanged between
the first and second computing devices in accordance with a key
exchange protocol, such that a key is derived at each of the first
and second computing devices using the password, and wherein the
one or more security parameters is transmitted to the second
computing device during the key exchange; wherein said performing
further comprises computing a confirmation value based on at least
the one or more security parameters, and using the key derived at
the first computing device, and transmitting the confirmation value
to the second computing device, wherein the one or more security
parameters are authenticated when the confirmation value is
successfully verified at the second computing device. In some
embodiments, the confirmation value comprises a keyed-hash message
authentication code. In some embodiments, the method performed at
the first computing device further comprises receiving one or more
second security parameters from the second computing device,
receiving a second confirmation value from the second computing
device, and verifying the second confirmation value.
In some embodiments, said transmitting the image or audio signal to
the second computing device is performed when the first and second
computing devices are in close physical proximity.
In some embodiments, the one or more security parameters comprise
one or more public keys stored on the first computing device. For
example, the one or more public keys may comprise a first public
key usable to encrypt messages to a user of the first computing
device, and a second public key usable to verify digital signatures
of messages digitally signed at the first computing device.
In some embodiments, the key exchange protocol comprises a Simple
Password Exponential Key Exchange (SPEKE) protocol.
In some embodiments, the image comprises a barcode. In some
embodiments, at the transmitting, the image is transmitted via a
display of the first computing device.
In some embodiments, the audio signal comprises a plurality of
audio tones. In some embodiments, at the transmitting, the audio
signal is transmitted via a speaker of the first computing device.
In some embodiments, at the transmitting, the audio signal is
transmitted via a channel established during a phone call between
the first computing device and the second computing device.
In some embodiments, the first data further comprises routing data
associated with the first computing device. In at least one
embodiment, the routing data associated with the first computing
device comprises a PIN associated with the first computing device,
and wherein the communication channel between the first and second
computing devices comprises a PIN-to-PIN channel.
In some embodiments, the method performed at the first computing
device further comprises generating the password, wherein the
password is generated as a random number or string. In at least one
embodiment, the password is generated for a single instance of said
generating the image or audio signal.
In some embodiments, at least one computing device selected from
the following group comprises a mobile device: the first computing
device, and the second computing device.
In another broad aspect, there is provided a system, device, and
method of transmitting one or more security parameters to a first
computing device from a second computing device, the method
performed at the second computing device, the method comprising:
receiving an image or audio signal, wherein the image or audio
signal is a representation of first data, the first data comprising
a password, wherein the password is not derived from a security
parameter stored on the first computing device; determining the
password from the image or audio signal; performing a key exchange
with the first computing device over a communication channel
between the first and second computing devices, wherein second data
is exchanged between the first and second computing devices in
accordance with a key exchange protocol, such that an encryption
key is derived at each of the first and second computing devices
using the password; encrypting the one or more security parameters
with the encryption key or a session key derived from the
encryption key; and transmitting the encrypted one or more security
parameters to the first computing device. In some embodiments, the
method performed at the second computing device further comprises
receiving one or more encrypted second security parameters from the
first computing device, and decrypting the one or more encrypted
second security parameters using the encryption key or a session
key derived from the encryption key.
In another broad aspect, there is provided a system, device, and
method of transmitting one or more security parameters to a first
computing device from a second computing device, the method
performed at the second computing device, the method comprising:
receiving an image or audio signal, wherein the image or audio
signal is a representation of first data, the first data comprising
a password, wherein the password is not derived from a security
parameter stored on the first computing device; determining the
password from the image or audio signal; and performing a key
exchange with the first computing device over a communication
channel between the first and second computing devices, wherein
second data is exchanged between the first and second computing
devices in accordance with a key exchange protocol, such that a key
is derived at each of the first and second computing devices using
the password, and wherein the one or more security parameters is
transmitted to the first computing device during the key exchange;
wherein said performing further comprises computing a confirmation
value based on at least the one or more security parameters, and
using the key derived at the second computing device, and
transmitting the confirmation value to the first computing device,
wherein the one or more security parameters are authenticated when
the confirmation value is successfully verified at the first
computing device. In some embodiments, the confirmation value
comprises a keyed-hash message authentication code. In some
embodiments, the method performed at the second computing device
further comprises receiving one or more second security parameters
from the first computing device, receiving a second confirmation
value from the first computing device, and verifying the second
confirmation value.
In some embodiments, said receiving the image or audio signal is
performed when the first and second computing devices are in close
physical proximity.
In some embodiments, the one or more security parameters comprise
one or more public keys stored on the second computing device. For
example, the one or more public keys may comprise a first public
key usable to encrypt messages to a user of the second computing
device, and a second public key usable to verify digital signatures
of messages digitally signed at the second computing device.
In some embodiments, the key exchange protocol comprises a SPEKE
protocol.
In some embodiments, the image comprises a barcode. In some
embodiments, at the receiving, the image is received via a camera
of the second computing device, wherein the camera is configured to
process the image after being displayed on a display of the first
computing device.
In some embodiments, the audio signal comprises a plurality of
audio tones. In some embodiments, at the receiving, the audio
signal is received via a microphone of the second computing device,
wherein the microphone is configured to receive the audio signal
after being output on a speaker of the first computing device. In
some embodiments, at the receiving, the audio signal is received
via a channel established during a phone call between the first
computing device and the second computing device.
In some embodiments, the first data further comprises routing data
associated with the first computing device. In some embodiments,
the method performed at the second computing device further
comprises establishing the communication channel by initiating
contact with the first computing device using the routing data. In
at least one embodiment, the routing data comprises a PIN
associated with the first computing device, and wherein the
communication channel between the first and second computing
devices comprises a PIN-to-PIN channel.
In some embodiments, the password comprises a random number or
string.
In some embodiments, at least one computing device selected from
the following group comprises a mobile device: the first computing
device, and the second computing device.
These and other aspects and features of various embodiments will be
described in greater detail below.
Reference is first made to FIG. 5, wherein a block diagram 500
illustrating the secure transmittal of security parameters from one
computing device to another computing device is shown, in
accordance with at least one embodiment.
A first computing device, such as a mobile device (e.g. mobile
device 100 of FIG. 1 represented as mobile device 100a), begins by
communicating a password 510 to a second computing device, such as
a mobile device (e.g. mobile device 100 of FIG. 1 represented as
mobile device 100b). An out-of-band communication path may be used
for communicating the password between the two computing devices to
provide greater security. Once both computing devices have the
password, a key exchange may then be performed between the first
computing device and the second computing device over a
communication channel between the two computing devices, which may
be different from the path used to communicate the password, in
accordance with a key exchange protocol 520.
In this embodiment, as part of the key exchange protocol 520, an
encryption key is derived at each of the first computing device and
the second computing device using password 510. The encryption key
or a session key derived from the encryption key 530a, 530b, may
then be used to encrypt one or more security parameters (e.g. one
or more public keys) or other data to be communicated, thereby
establishing an encrypted session 540 over the communication
channel between the two computing devices.
The secure transmittal of security parameters from one computing
device to another computing device in accordance with at least one
embodiment will be described in further detail below.
Referring to FIG. 6, a flowchart illustrating acts of a method 600
of securely transmitting a security parameter from one computing
device to another computing device (e.g. as previously described
with reference to FIG. 5) is shown, in accordance with at least one
embodiment.
In the example embodiments described herein, for illustrative
purposes, it is assumed that a first computing device, such as a
mobile device (e.g. mobile device 100 of FIG. 1 represented as
mobile device 100a), initiates the transmittal of security
parameters. However, persons skilled in the art will appreciate
that another computing device, such as a different mobile device
(e.g. mobile device 100 of FIG. 1 represented as mobile device
100b), may initiate the transmittal of security parameters and,
therefore, the acts of method 600 performed at the first computing
device may alternatively be performed by a different computing
device.
In at least one embodiment, at least some of the acts of method 600
are performed by a processor executing an application (e.g.
comprising one or more application modules) residing on a computing
device, such as a mobile device (e.g. mobile device 100 of FIG. 1).
In variant embodiments, the application may reside on a computing
device other than a mobile device.
At 605, a password is optionally generated at the first computing
device. The password may comprise a number, an alphanumeric string
(e.g. comprising letters, numbers, and/or symbols), or data in some
other suitable format.
The password may be manually generated (e.g. entered as user input
in a user interface by a user of the first computing device), or it
may be randomly generated (e.g. by a random password generator). In
some embodiments, the password may comprise, for example, 32-bits
of randomly generated data. The use of randomly generated passwords
may provide for added security over the use of manually generated
passwords, as randomly generated passwords may typically be more
cryptographically complex than manually generated passwords. For
example, a random password generator could be configured to
generate a random password comprising a combination of lower and
upper case letters, numbers and punctuation symbols which would
typically have a higher strength (i.e. higher information entropy)
than a manually generated password and may be more difficult for an
attacker to try and guess than a manually generated password.
The password may be a password generated specifically for this
instance (e.g. this may be referred to as a "short-term" or
"ephemeral" password) or it may be a password that is also used for
some other purpose (e.g. this may be referred to as a "long-term"
password). Unlike long-term passwords that may be repeatedly used
(e.g. for some other purpose such as user authentication), a
short-term password may be generated afresh for each instance in
which a computing device is to initiate acts of a method for
securely transmitting a security parameter to another computing
device, in accordance with an embodiment described herein. As
compared with long-term passwords, short-term passwords may prevent
an attacker from using the previous communication history of a
computing device to reconstruct the password, since the password is
generated afresh for each new instance. Furthermore, since
short-term passwords are generated afresh for each new instance,
the password will not typically be pre-stored on the computing
device (e.g. in a non-volatile memory). This may prevent an
attacker from hacking into the computing device to obtain the
password.
At 610, an image or audio signal is generated at the first
computing device for transmission to the second computing device at
615, wherein the image or audio signal is a representation of first
data, the first data comprising a password (e.g. the password
generated at 605).
In at least one embodiment, the password is not derived from a
security parameter (e.g. a public key) associated with a user of
the first computing device (e.g. the password is not one of the
security parameters itself or a hash thereof). Put another way, the
password and the one or more security parameters are independent of
each other. In these embodiments, the present inventors recognized
that it may not be desirable to use a password that is derived from
a security parameter if enhanced security is desirable.
By not communicating data initially that is related to a security
parameter (e.g. a public key) of the first computing device, this
might add an additional layer of security and provide other
benefits. A potential disadvantage of transmitting a security
parameter is that an attacker can intercept the communication and
obtain the security parameter. A potential disadvantage of
transmitting a hash of a security parameter is that an attacker who
intercepts the communication and obtains the hash of the security
parameter might try all possibilities of the security parameter and
compare each guess with the hash in order to reconstruct the
security parameter. Moreover, another potential disadvantage of
transmitting a security parameter or hash thereof relates to the
resultant size of the binary representation of the security
parameter or hash thereof that is to be communicated. For example,
a binary representation of a 512-bit elliptic curve public key may
require about 66 bytes. Persons skilled in the art will appreciate
that a password may typically be generated as one that is shorter
in length than a security parameter (e.g. a public key) or hash
thereof, and therefore, less data would need to be transmitted by
the first computing device to the second computing device.
Transmission of a short password may also consume less computing
resources (e.g. bandwidth, time, processing power, etc.) than
transmission of a security parameter or hash thereof, which may be
particularly beneficial when, for example, the first computing
device (and/or the second computing device) comprises a mobile
device.
In at least one embodiment, each of one or more security parameters
(e.g. one or more public keys) associated with a user of either the
first computing device or the second computing device is not
derivable from the password. Persons skilled in the art will
appreciate that in order for a security parameter (e.g. a public
key) to be derivable from a password, the password would need to be
more complex than the security parameter. By having the security
parameter not be derivable from the password, this allows for the
use of a smaller, perhaps cryptographically weaker, password to
bootstrap into a larger cryptographically stronger encryption
key.
First data may additionally comprise routing data associated with
the first computing device. The routing data may be such data that
identifies a computing device, so that it may be contacted by
another computing device to establish a communication channel.
In at least some embodiments, the routing data associated with the
first computing device may comprise a PIN associated with the first
computing device. For example, a PIN is typically a unique personal
identification number identifying a particular computing device.
The PIN may be assigned at the time of manufacture, for example. In
other example embodiments, the routing data may comprise an IP
address and port number, or MAC address and subnet mask, or
Bluetooth device address, or phone number, or SMS address, for
example. The PIN may comprise 8 hexadecimal-ASCII characters, for
example.
First data may also optionally comprise additional identifying
information of the first computing device or a user thereof. For
example, such identifying information may include, but is not
limited to, the name of the user of the first computing device, the
name of a group of which the user of the first computing device is
a member and is seeking to invite the user of the second computing
device to join, the type of the group (e.g. "friend", "family", or
"work"), a unique identifier for the particular key exchange
request (e.g. as initiated at 615), or a timestamp or expiry data
(e.g. to indicate when a key exchange must be completed by), or
some combination of the above, for example.
In at least one embodiment, the image may comprise a barcode that
is a representation of first data (e.g. the password generated at
605), for example. A barcode is a visual representation of
information, as known in the art. For example, a barcode may
comprise a 1-dimensional barcode represented by a series of lines
of varying widths and spacing. As a further example, barcode may
comprise a 2-dimensional barcode represented by squares, dots,
hexagons or other geometric patterns. In some embodiments, the
barcode may be a black and white barcode. In other embodiments, the
barcode may be a color barcode.
In at least one embodiment, the audio signal may comprise a
plurality of audio tones that is a representation of first data,
for example. The plurality of audio tones may comprise a Dual Tone
Multiple Frequency (DTMF) sequence, for example.
In some embodiments, the generation of the image or audio signal at
610 may be made based on user input provided via a user interface,
in which the user of the first computing device may be presented
with a dialog box prompting him or her to generate the image or
audio signal.
At 615, the image or audio signal generated at 610 is transmitted
to the second computing device. At 620, the image or audio signal
(which comprises a representation of first data, the first data
comprising, for example, a password and may additionally comprise
routing data and/or other identifying information) transmitted from
the first computing device at 615 is received at the second
computing device.
In one embodiment, the image may be transmitted via a display
associated with the first computing device at 615. The display may
either reside on the first computing device itself or may be a
separate device coupled to the first computing device. The image
may be received via a camera or other optical sensing device
associated with the second computing device at 620. The camera or
other optical sensing device may either reside on the second
computing device itself or may be a separate device coupled to the
second computing device. In this embodiment, the camera or other
optical sensing device is configured to process the image (e.g.
photograph the image or scan the image) transmitted from the first
computing device, the image being captured after the image is
displayed on the display associated with the first computing
device.
Persons skilled in the art will appreciate that the image may be
transmitted and received using other means in variant embodiments.
For example, the image may be transmitted and received as an image
file through a wired connection established between the first
computing device and the second computing device. As a further
example, the image may be transmitted as a printout to a printer,
wherein the printer may either reside on the first computing device
itself or may be a separate device coupled to the first computing
device. The image may then be received by the second computing
device through a scanner that scans the image, wherein the scanner
may either reside on the second computing device itself or may be a
separate device coupled to the second computing device.
The audio signal may be transmitted via a speaker (or e.g. an
earpiece) associated with the first computing device at 615,
wherein the speaker may either reside on the first computing device
itself or may be a separate device coupled to the first computing
device. The audio signal may be received via a microphone
associated with the second computing device at 620, wherein the
microphone may either reside on the second computing device itself
or may be a separate device coupled to the second computing device,
and the microphone is configured to process the audio signal (e.g.
record the audio signal) transmitted from the first computing
device (e.g. the audio signal being captured after the audio signal
is played on the speaker associated with the first computing
device).
Persons skilled in the art will appreciate that the audio signal
may be transmitted and received using other means in variant
embodiments. For example, the audio signal may be transmitted and
received as an audio file through a wired connection established
between the first computing device and the second computing device.
As a further example, the audio signal may be transmitted through a
phone call (e.g. a voice call) over a channel established between
the first computing device and the second computing device,
although this embodiment may provide less security than that
provided by other embodiments described herein depending on whether
the channel is secure from eavesdropping.
In some embodiments, the first computing device may be in close
physical proximity to the second computing device when the image or
audio signal is to be transmitted. By transmitting and receiving
the image or audio signal when the first computing device and
second computing device are in close physical proximity to each
other, and representing first data in a form that requires the two
computing devices to be in close physical proximity to one another
in order for the first data to be successfully transmitted, an
added layer of security may be provided. For instance, the users of
both computing devices can better ensure that they are
communicating with each other's computing device only, and not the
computing device of an attacker.
For example, the user of the first computing device can better
ensure that the intended recipient, the user of the second
computing device, has received the image or audio signal (e.g. the
acts of a method in accordance with an embodiment described herein
may be initiated when the user of the first and second computing
devices are "face-to-face"), and reduce the risk that the image or
audio signal will be unknowingly intercepted. Similarly, the user
of the second computing device can ensure that the image or audio
signal is received from the intended sender, the user of the first
computing device, and not from the computing device of an attacker
posing as the user of the first computing device. Accordingly,
authenticity and confidentiality of the password can be generally
maintained, as the authenticity and confidentiality of the image or
audio signal that is a representation of first data comprising the
password can be maintained.
Where the password, for example, is represented in an image that is
being transmitted and received, the user of the first computing
device and the user of the second computing device can ensure that
there is no one else (i.e. a possible attacker) within a line of
sight of the image as it is transmitted (e.g. via a display
associated with the first computing device) and received (e.g. via
a camera associated with the second computing device).
Where the password, for example, is represented in an image that is
being transmitted and received, two computing devices may be in
close physical proximity when, for example, they are at a
sufficient distance such that when the image is transmitted by one
computing device (e.g. via a display), it may be received at the
other computing device (e.g. via a camera), and processed by the
other computing device to determine the first data without error.
For example, a greater distance between the two computing devices
may be accommodated where the display associated with the first
computing is larger, and/or where the camera associated with the
second computing device is capable of capturing images accurately
at a greater distance.
As another example, where the password, for example, is represented
as an audio signal that is being transmitted and received, the user
of the first computing device and the user of the second computing
device can ensure that there is no one else (i.e. a possible
attacker) that may potentially eavesdrop on the audio signal as it
is transmitted (e.g. via a speaker associated with the first
computing device) and received (e.g. via a microphone associated
with the second computing device).
Where the password, for example, is represented in an audio signal
that is transmitted and received, two computing devices may be in
close physical proximity when, for example, they are at a
sufficient distance such that when the audio signal is transmitted
by one computing device (e.g. via a speaker), it may be received at
the other computing device (e.g. via a microphone), and processed
by the other computing device to determine the first data without
error. For example, a greater distance between the two computing
devices may be accommodated where the speaker associated with the
first computing device provides greater amplification, and/or where
the microphone associated with the second computing device is more
sensitive.
By transmitting and receiving the image or audio signal in the
manner described above, extensive user involvement need not be
required. The user of the first computing device need not manually
enter information about the second computing device or a user
thereof in order to transmit the image or audio signal. For
example, the user of the first computing device need not manually
enter routing data associated with the second computing device to
establish a communication channel in order to transmit the image or
audio signal. Moreover, the user of the second computing device
need not manually type the password into his or her computing
device in at least one embodiment. In order to transmit the image
or audio signal, the first computing device may be simply directed
by the user to display the image, for example, or play the audio
signal, for example. The first computing device may be configured
to generate at least some or all of the first data, and represent
it in the form of the image or audio signal, automatically in
response to the user direction.
Moreover, by transmitting and receiving an image or audio using an
out-of-band communication path, security may be enhanced. By
transmitting a password in the form of an image or audio signal,
the password, as represented by the image or audio signal, may be
utilized by both computing devices to bootstrap to a larger
cryptographically strong encryption key.
Referring again to FIG. 6, at 625, the first data is determined
from the image or audio signal at the second computing device. As
previously described, the image or audio signal is a representation
of first data. In other words, the password, and perhaps routing
data and/or other identifying information may be recovered from the
image or audio signal received, so that it may be further processed
at the second computing device.
In some embodiments, the user of the second computing device may be
presented with an option (e.g. via a dialog box in a user
interface) as to whether to continue with the remaining acts of
method 600 (e.g. to perform a key exchange with the first computing
device at 630). This option may be provided to the user of the
second computing device to confirm that the key exchange (acts 628
to 645) should be performed. For example, where the user of the
first computing device may be inviting the user of the second
computing device to join a group, and where it would be prudent to
warn the user of the second computing device that his or her device
may be subject to certain controls if he or she agrees to join the
group, it may be desirable to give him or her the option of
declining the key exchange. Where an option is presented to the
user of the second computing device and the user decides not to
continue with the key exchange, remaining acts of method 600 are
not performed.
Alternatively, the key exchange may be performed automatically once
the user has activated a device (e.g. camera or microphone) to
capture the image or audio signal (at 620).
In at least some embodiments, establishment of the communication
channel is initiated by the second computing device, which contacts
the first computing device at 628. In establishing the
communication channel with the first computing device, routing data
pre-stored on the second computing device (e.g. in an address book)
or routing data recovered from the first data received at 620 may
be used, for example.
In at least one embodiment, where the routing data associated with
the first computing device may comprise a PIN associated with the
first computing device, the communication channel between the first
and second computing device may comprise a peer-to-peer channel
such as a PIN-to-PIN channel.
A key exchange is performed between the first and second computing
devices (630, 640) over a communication channel established between
the two computing devices (e.g. the communication channel
established by the second computing device after contacting the
first computing device as identified by the routing data at 628, or
some other communication channel) in accordance with a key exchange
protocol. The key exchange may involve exchanges of second data
between the first and second computing devices, in accordance with
the key exchange protocol (e.g. data required to complete the key
exchange, which may include for example, the transfer of computed
intermediate values in accordance with the key exchange
protocol).
Although act 628 is shown as a separate act in FIG. 6, in at least
some embodiments, the initiation of the establishment of the
communication channel at 628 may be an act performed as a part of
the key exchange performed by the second computing device at 640.
The communication channel may be established over, for example, a
WAN network (e.g. the Internet), an Intranet, an 802.11 or
Bluetooth link, which may be insecure. As noted above, in one
embodiment, the communication channel may be a peer-to-peer channel
such as a PIN-to-PIN channel.
As a result of the key exchange, an encryption key may be derived
at each of the first and second computing devices (635, 645).
Subsequent to the key exchange between the first and second
computing devices at 630 and 640, any further communication of data
between the first computing device and the second computing device
over an otherwise insecure communication channel may be secured
using the encryption key derived at each computing device at 635
and 645, or a session key derived from that encryption key derived
at each computing device.
The key exchange protocol performed at 630 and 640 may be a
cryptographic method for password-authenticated key agreement (e.g.
cryptographic keys may be established by one or more parties based
on their knowledge of a shared password).
Since the key exchange protocol performed at 630 and 640 is based
on a shared password (i.e. password-authenticated key agreement)
and the password is independent of the security parameters (e.g.
public keys), a key exchange protocol based on public keys or
hashes thereof (e.g. Secure Socket Layer/Transport Layer Security
(SSL/TLS), Secure Key Exchange Mechanism (SKEME), Internet Key
Exchange (IKE), etc.) need not be utilized in at least one
embodiment described herein.
In some embodiments, the key exchange protocol performed at 630 and
640 may comprise the SPEKE protocol. The SPEKE protocol is one
example of a cryptographic method for password-authenticated key
agreement, which on the basis of a shared password, allows parties
to derive the same encryption key (i.e. a SPEKE established key)
for sending secure and authenticated communications to each other,
over what may be an otherwise insecure communication channel. The
SPEKE protocol may involve a password-authenticated Diffie-Hellman
exchange, where the password forms the base or "generator" of the
exchange.
In other embodiments, the key exchange protocol may comprise
variants of the SPEKE protocol. In other embodiments, the key
exchange protocol, which may be SPEKE or variants thereof, may be
combined with other compatible key exchange protocols to provide
additional layers of security. Persons skilled in the art will
appreciate that by using SPEKE or variants thereof, fewer data
exchanges may be required to complete the key exchange when
compared to the use of other protocols (e.g. SSL/TLS).
Other examples of key exchange protocols based on a shared password
which may be utilized include, for example, encrypted key exchange
(EKE), password authenticated key exchange by juggling (J-PAKE) and
Password Derived Moduli (PDM) to name a few.
Optionally, at 650, where the first computing device (or a user
thereof) wishes to transmit one or more security parameters (e.g.
one or more public keys) to a second computing device (or a user
thereof), the one or more security parameters may be encrypted with
the encryption key derived at 635 or a session key derived from the
encryption key derived at 635. Accordingly, at 660a, the one or
more encrypted security parameters may be transmitted from the
first computing device to the second computing device. At 665a, the
one or more encrypted security parameters may be received at the
second computing device from the first computing device. Upon
receiving the one or more encrypted security parameters from the
first computing device, the second computing device may decrypt the
one or more encrypted security parameters using the encryption key
derived at 645 or a session key derived from the encryption key
derived at 645 to retrieve the one or more security parameters of
the first computing device.
Optionally, at 655, where the second computing device (or a user
thereof) wishes to transmit one or more security parameters (e.g.
one or more public keys) to a first computing device (or a user
thereof), the one or more security parameters may be encrypted with
the encryption key derived at 645 or a session key derived from the
encryption key derived at 645. Accordingly, at 665b, the one or
more encrypted security parameters may be transmitted from the
second computing device to the first computing device. At 660b, the
one or more encrypted security parameters may be received at the
first computing device from the second computing device. Upon
receiving the one or more encrypted security parameters from the
second computing device, the first computing device may decrypt the
one or more encrypted security parameters using the encryption key
derived at 635 or a session key derived from the encryption key
derived at 635 to retrieve the one or more security parameters of
the second computing device.
Persons skilled in the art will appreciate that in different
situations, one or more security parameters may be transmitted from
the first computing device to the second computing device (e.g.
acts 660a and 665a are performed), from the second computing device
(e.g. acts 660b and 665b are performed) to the first computing
device, or both ways (e.g. acts 660a, 660b, 665a and 665b are
performed).
In some embodiments, the one or more security parameters may
comprise one or more public keys associated with a user of either
the first computing device or the second computing device. As
described previously with reference to FIG. 4, data signed using a
private key of a private key/public key pair can only be verified
using the corresponding public key of the pair, and data encrypted
using a public key of a private key/public key pair can only be
decrypted using the corresponding private key of the pair.
For example, once the user of a first computing device has the
public key of the user of a second computing device, the user of
the first computing device may then send encrypted messages to the
user of the second computing device. As a further example, once the
user of a first computing device is reasonably certain that his
public key has been received by the second computing device, the
user of the first computing device may then digitally sign messages
to be sent to the user of the second computing device.
Similarly, once the user of a second computing device has the
public key of the user of a first computing device, the user of the
second computing device may then send encrypted messages to the
user of the first computing device. As a further example, once the
user of a second computing device is reasonably certain that his
public key has been received by the first computing device, the
user of the second computing device may then digitally sign
messages to be sent to the user of the first computing device.
Multiple public keys (and corresponding private keys) may be
transmitted from the first computing device to the second computing
device, from the second computing device to the first computing
device, or both. For example, two public keys may be associated
with the same user of a given computing device. A first public key
may be usable to encrypt messages to a user of the given computing
device, and a second public key may be usable to verify digital
signatures of messages digitally signed at the given computing
device. Different public keys may be employed for different
purposes, and the one or more security parameters being transmitted
from one computing device to another may comprise a plurality of
said different public keys.
FIG. 7 is a flowchart illustrating at least one variant embodiment
that is similar to method 600 shown in FIG. 6. Generally,
embodiments of the method illustrated by the flowchart in FIG. 7
are similar to embodiments of the method illustrated by the
flowchart in FIG. 6, except that some acts of the key exchange
protocol and the transmittal of security parameters are
intertwined, as described in further detail below. By intertwining
acts of the key exchange protocol and the transmittal of security
parameters, this may provide an advantage of not requiring as many
communication passes in order to effect the exchange of security
parameters between the first and second computing devices.
In one variant embodiment, the security parameters are transmitted
in unencrypted form. The present inventors recognized that where
the one or more security parameters to be transmitted comprises one
or more public keys, there would be no need to keep the data secret
(and therefore encrypt it) because it is already "public"
information (i.e. anyone may have access to it). However, when one
or more security parameters are received at a given computing
device, it is still typically desirable to ensure that the received
security parameters are authentic. In this variant embodiment,
although a key is derived at each computing device in accordance
with a key exchange protocol (e.g. the SPEKE protocol), this key is
not used as an encryption key per se (as in method 600 of FIG. 6),
but is instead used as a key for deriving a value that may be
verified in order to authenticate the security parameters being
exchanged.
Acts 705, 710, and 715 are analogous to acts 605, 610 and 615 of
FIG. 6, respectively, and the reader is directed to the description
of FIG. 6 above for further details in respect of acts 705, 710,
and 715. Similarly, acts 720, 725, and 728 are analogous to acts
620, 625, and 628 of FIG. 6, respectively, and the reader is
directed to the description of FIG. 6 above for further details in
respect of acts 720, 725, and 728.
A key exchange is performed between the first and second computing
devices (730, 740) over a communication channel established between
the two computing devices (e.g. the communication channel
established by the second computing device after contacting the
first computing device as identified by the routing data at 728, or
some other communication channel) in accordance with a key exchange
protocol. The key exchange may involve exchanges of second data
between the first and second computing devices, in accordance with
the key exchange protocol (e.g. data required to complete the key
exchange, which may include for example, the transfer of computed
intermediate values in accordance with the key exchange protocol).
For ease of exposition, the acts of the key exchange will be
described in FIG. 7 with reference to the SPEKE protocol, although
it will be understood by persons skilled in the art that other key
exchange protocols might be employed in variant embodiments.
Although act 728 is shown as a separate act in FIG. 7, in at least
some embodiments, the initiation of the establishment of the
communication channel at 728 may be an act performed as a part of
the key exchange performed by the second computing device at 740.
The communication channel may be established over, for example, a
WAN network (e.g. the Internet), an Intranet, an 802.11 or
Bluetooth link. As previously described, in one embodiment, the
communication channel may be a peer-to-peer channel such as a
PIN-to-PIN channel.
At 732, one or more intermediate keys may be derived at the first
computing device using the password as part of the key exchange
protocol. Similarly, at 742, one or more intermediate keys may be
derived at the second computing device using the password as part
of the key exchange protocol. The one or more intermediate keys
derived using the password may be, for example, a SPEKE private
key/public key pair where the key exchange protocol performed at
730 and 740 is the SPEKE protocol.
At 744, an intermediate key derived at the second computing device
(e.g. a SPEKE public key) is transmitted from the second computing
device to the first computing device, where it is received at 734.
Where the second computing device (or a user thereof) wishes to
transmit one or more security parameters (e.g. one or more public
keys associated with a user of the second computing device and
intended for subsequent use in encoding messages) to a first
computing device (or a user thereof), the one or more security
parameters may also be transmitted from the second computing device
to the first computing device, at 744, where it is received, at
734.
At 736, a further key may be derived at the first computing device
in accordance with the key exchange protocol. This further key may
be, for example, a SPEKE established key, where the key exchange
protocol performed at 730 and 740 is the SPEKE protocol. As is
known, the SPEKE established key derived at the first computing
device is a function of the SPEKE public key derived at the second
computing device, which is received from the second computing
device at 734, and the SPEKE private key derived at the first
computing device at 732.
At 738, a confirmation value is derived at the first computing
device using the key derived at 736 (e.g. SPEKE established key).
The confirmation value may be a Keyed-Hash Message Authentication
Code (HMAC), for example, which uses the key derived at 736 and a
hash computed using at least some of the data exchanged (or to be
exchanged) with the second computing device.
For example, at 738, an HMAC may be computed at the first computing
device using the key derived at 736, and a hash computed based on
the following data: at least some of the first data transmitted to
the second computing device at 715 (e.g. a group name, group type,
invitation ID, a PIN associated with the first computing device),
although the password need not be included in the hashed data; one
or more security parameters (e.g. one or more public keys for
message encoding) received from the second computing device at 734;
and one or more security parameters (e.g. one or more public keys
for message encoding) to be transmitted from the first computing
device to the second computing device at 750. Those skilled in the
art will appreciate that the data included in the hash may not
include all of the information identified above, and may include
additional data not identified above. Generally, the confirmation
value derived at the first computing device may be derived as an
HMAC computed by hashing all of the data exchanged in the protocol,
in combination with the SPEKE established key derived at the first
computing device.
At 750, an intermediate key derived at the first computing device
at 732 (e.g. a SPEKE public key) is transmitted from the first
computing device to the second computing device, where it is
received at 746. Where the first computing device (or a user
thereof) wishes to transmit one or more security parameters (e.g.
one or more public keys associated with a user of the first
computing device and intended for subsequent use in encoding
messages) to a second computing device (or a user thereof), the one
or more security parameters may also be transmitted from the first
computing device to the second computing device, at 750, where it
is received, at 746. Additionally, at 750, the confirmation value
may also be transmitted from the first computing device to the
second computing device, where it is received at 746.
At 748, a further key may be derived at the second computing device
in accordance with the key exchange protocol. This further key may
be, for example, a SPEKE established key, where the key exchange
protocol performed at 730 and 740 is the SPEKE protocol. In
accordance with SPEKE, the SPEKE established key derived at the
first computing device at 736, and the SPEKE established key
derived at the second computing device at 748, are expected to
match.
At 754, a confirmation value is derived at the second computing
device using the key derived at 748 (e.g. SPEKE established key).
Similar to act 738 performed at the first computing device, the
confirmation value may be an HMAC, for example, computed using the
key derived at 748 and a hash computed using at least some of the
data exchanged (or to be exchanged) with the first computing
device.
For example, at 754, an HMAC may be computed at the second
computing device using the key derived at 748, and a hash computed
based on the following data: at least some of the first data
received from the first computing device at 720 (e.g. a group name,
group type, invitation ID, a PIN associated with the first
computing device), although the password need not be included in
the hashed data; one or more security parameters (e.g. one or more
public keys for message encoding) transmitted to the first
computing device at 744; and one or more security parameters (e.g.
one or more public keys for message encoding) received from the
first computing device at 746. Those skilled in the art will
appreciate that the data included in the hash may not include all
of the information identified above, and may include additional
data not identified above. Generally, the confirmation value
derived at the second computing device may be derived as an HMAC
computed by hashing all of the data exchanged in the protocol, in
combination with the SPEKE established key derived at the second
computing device.
At 756, the confirmation value derived at 754 may be transmitted
from the second computing device to the first computing device,
where it is received at 752.
At 758 and 760, the confirmation value received at each of the
first and second computing devices is verified at the respective
computing device. If the confirmation value received is
successfully verified at a given computing device (i.e. it is
confirmed that the value is what it is expected to be, given that
both computing devices know how the various confirmation values are
computed), then the security parameters (e.g. one or more public
keys used for message encoding) received at that given computing
device from the other computing device may be considered to be
authentic. If the confirmation value does not successfully verify
(e.g. an HMAC will not be calculated accurately if the exchanged
data has been tampered with in transit), then the security
parameters will fail to be authenticated.
In at least some embodiments, the confirmation value derived at the
first computing device and the confirmation value derived at the
second computing device are computed so that they are different.
This is done intentionally by introducing known values in the
computation of the confirmation values (e.g. HMACs), and may
provide added security by preventing replay attacks where the
second computing device (i.e. the joiner) might simply re-transmit
a confirmation value computed at and received from the first
computing device (i.e. the inviter). For example, the hash used to
derive the confirmation value at the first computing device, at
738, may additionally be based on data that comprises a specific
known value (e.g. the byte 0x03). Similarly, the hash used to
derive the confirmation value at the second computing device, at
754, may additionally be based on data that comprises a specific,
but different known value (e.g. the byte 0x02). Accordingly, the
confirmation value derived at the first computing device may be an
HMAC computed based on all exchanged data plus a specific known
value associated with the first computing device, using the SPEKE
established key derived at the first computing device. Similarly,
the confirmation value derived at the second computing device may
be an HMAC computed based on all exchanged data plus a different,
specific known value associated with the second computing device,
and using the SPEKE established key derived at the second computing
device. Although the confirmation values derived at each of the
computing devices will be different, since the hash is additionally
based on known values, the confirmation values can still be
verified at both computing devices.
Although the method 700 illustrated in FIG. 7 is described above
with reference to the SPEKE protocol as the key exchange protocol,
persons skilled in the art will appreciate that variants of SPEKE
and other key exchange protocols based on a shared password may
also be utilized.
Persons skilled in the art will understand that method 700 may be
modified to accommodate situations where only one of the first and
second computing devices transmits one or more security parameters
to the other of the first and second computing devices, in variant
embodiments.
As previously noted, persons skilled in the art will also
appreciate that more than one security parameter may be transmitted
in accordance with the embodiments described herein. Furthermore,
the one or more security parameters are not limited to public keys,
and may comprise, for example, other data which could then be used
to provide authenticity and confidentiality for further
communication between the two computing devices. In some
embodiments, multiple public keys may be transmitted in accordance
with the embodiments described herein, with a different public key
for a specific purpose. For example, the one or more public keys
may comprise a first public key usable to encrypt messages to a
user of the first computing device, and a second public key usable
to verify digital signatures of messages digitally signed at the
first computing device.
The embodiments described herein do not require a public key
infrastructure in order to allow users of computing devices to
transmit public keys to, and receive public keys from, each
other.
The embodiments described herein also do not require manual
verification of a public key (e.g. a user checking and confirming
the public key fingerprint), which may require extensive user
involvement.
Also, when the computing devices in the embodiments described above
are mobile devices, since mobile devices are generally portable
handheld devices which can easily be brought physically close to
one another, there may be more instances when users of mobile
devices may want to exchange public keys or other security
parameters on the spur of the moment (e.g. if two users, previously
unknown to each other, meet at a party or some other setting), in
accordance with one or more embodiments described herein.
Although the embodiments described herein relate to the
transmission and reception of an image or audio signal that is a
representation of first data, in variant embodiments, first data
may be transmitted in an electronic mail (i.e. e-mail) message. In
these embodiments, the first data may be transmitted as an e-mail
message with the password contained in the message itself. In
variant embodiments, the first data may be transmitted as an e-mail
message with a hint to a password. Where a hint for the password is
contained in the message, the users of the two computing devices
who wish to exchange security parameters should know a priori what
the password may be, with the hint of the password providing a
suggestion to the user of the second computing device as to what
the password is. The user of the second computing device may then
manually enter the password in a user interface of an application
or confirm that the password is to be used in order to initiate the
security parameter transmittal process on his or her computing
device. In variant embodiments, the first data may be transmitted
in a peer-to-peer message, such as a PIN message, in a similar
manner.
In variant embodiments, the first data transmitted from the first
device to the second computing device (e.g. 615 of FIG. 6, 715 of
FIG. 7), may be transmitted in the form of a medium other than an
image or audio signal. For example, the first data may be
transmitted in the form of an infrared signal, to be received at
the receiving computing device using appropriate hardware.
The acts of method 600 of transmitting security parameters in
accordance with an embodiment described herein may be provided as
executable software instructions stored on computer-readable
storage media.
The acts of method 600 of transmitting security parameters in
accordance with an embodiment described herein may be provided as
executable software instructions stored on transmission-type
media.
By way of illustration, FIGS. 8 to 10 are example screen captures
of a display (e.g. display 110 of FIG. 1) of the first computing
device (e.g. mobile device 100 of FIG. 1) as a method of
transmitting security parameters (e.g. method 600 of FIG. 6 or
method 700 of FIG. 7) is performed in accordance with an example
embodiment.
FIG. 8 is an example screen capture 800 of the display of the first
computing device prompting a user with an option to generate either
an image (e.g. a barcode) or an e-mail message (e.g. act 610 of
FIG. 6 or act 710 of FIG. 7). For example, in the user interface
800, the user may select a first option 810, "Show them a barcode",
to generate an image (e.g. a barcode), or a second option 820,
"Send them a message".
FIG. 9 is an example screen capture 900 of the display of the first
computing device wherein a user has selected an option to generate
an image (e.g. a barcode). For example, a user of the first
computing device may provide instructional text 910 and/or
instructional diagrams 920 to instruct a user to transmit the image
(e.g. a barcode) from the first computing device to the second
computing device.
FIG. 10 is an example screen capture 1000 of the display of the
first computing device as it displays an image (e.g. a barcode)
1010 for transmission to the second computing device (see e.g. act
615 of FIG. 6 or act 715 of FIG. 7).
By way of further illustration, FIGS. 11 to 13 are example screen
captures of a display (e.g. display 110 of FIG. 1) of the second
computing device (e.g. mobile device 100 of FIG. 1) as a method of
transmitting security parameters (e.g. method 600 of FIG. 6 or
method 700 of FIG. 7) is performed in accordance with an example
embodiment.
FIG. 11 is an example screen capture 1100 of the display of the
second computing device prompting a user with an option to receive
the transmission of an image (e.g. a barcode) from the first
computing device (see e.g. act 620 of FIG. 6 or act 720 of FIG. 7).
For example, in a user interface of the second computing device,
the user may select an option 1110, "Join a group by scanning a
barcode", to begin receiving the image (e.g. a barcode).
FIG. 12 is an example screen capture 1200 of the display of the
second computing device as it instructs a user on how to receive an
image (e.g. a barcode) from the first computing device. For
example, a user interface of the second computing device may
provide instructional text 1210 and/or instructional diagrams 1220
to instruct a user on how to receive the image from the first
computing device at the second computing device.
FIG. 13 is an example screen capture 1300 of the display of the
second computing device upon receiving an image (e.g. a barcode)
transmitted from the first computing device, and upon determining
first data from the image, such as a barcode for example (see e.g.
act 625 of FIG. 6 or act 725 of FIG. 7). For example, a user
interface of the second computing device may provide a prompt 1310
to a user to confirm whether to continue with the key exchange. The
prompt may show the routing data associated with the first
computing device (e.g. a PIN associated with the first computing
device). The prompt may also show other identifying information of
the first computing device or a user thereof (e.g. that the user of
the first computing device is a member of the Work group "Group
C"). Where the user wishes to continue, the user may indicate
his/her acceptance by selecting a confirmation option 1320, "Join
Group", for example. This may allow the user to communicate with
other members who have joined the group securely, using the
security parameter(s) to be exchanged. Where the user does not wish
to continue with the remaining acts of method 600 or method 700,
the user may abort by selecting a cancellation option 1330,
"Cancel", for example.
By way of further illustration, FIG. 14 is an example screen
capture 1400 of a display of the first computing device wherein a
user has selected an option to generate a message, instead of an
image or audio signal, in accordance with a variant embodiment
previously described herein. For example, in a user interface of
the first computing device, the user of the first computing device
may be prompted to enter in a text field 1410 either the name,
email address or PIN, for example, of the second computing device
or a user thereof. The user of the first computing device may be
prompted to enter in a text field 1420 the password itself and/or a
hint for the password in a text field 1430. An e-mail message or
PIN message or other types of message addressed to a user of the
second computing device may then be sent (e.g. in response the user
of the first computing device selecting a send option 1440, "Send
invitation").
It will be understood that while examples have been presented
herein illustrating embodiments of a method where two computing
devices are involved, more than two computing devices may be
involved in variant implementations. For example, a user may invite
multiple people to join a private group, so that everyone in the
private group can communicate with each other. To facilitate this,
the same barcode may be shown to multiple invitees, or a different
barcode may be shown to each invitee.
As used herein, the wording "and/or" is intended to represent an
inclusive-or. That is, "X and/or Y" is intended to mean X or Y or
both. Moreover, "X, Y, and/or Z" is intended to mean X or Y or Z or
any combination thereof.
A number of embodiments have been described herein. However, it
will be understood by persons skilled in the art that other
variants and modifications may be made without departing from the
scope of the claimed embodiments appended hereto.
* * * * *